Exam 3 Flashcards
The phenotypic ratio for the F1 generation that results from a test cross between
a homozygous recessive individual and a heterozygous individual is
1:1
Alternate forms of the same gene are called
alleles
Individuals that have two alleles for most gene loci are best described as
diploid
The observable outward manifestation of the genes of an individual is referred
to as its
phenotype
Let P = purple flowers and p = white, and T = tall plants and t = dwarf. What are
the genotypes of the gametes that are produced by a plant that is heterozygous
for both traits?
PT, Pt, pT, and pt
Let P = purple flowers and p = white, and T = tall plants and t = dwarf. Of the 16
possible gamete combinations in the dihybrid cross between two heterozygotes,
how many would produce the phenotype white, tall?
3
In white tigers, the absence of fur pigmentation is caused by a recessive allele
that also causes the tigers to be cross-eyed. If two tigers are heterozygous for
this allele mate, What do you expect to see among the offspring?
¼ will be both white and cross-eyes, ¾ will be orange with normal eyes
Let R = red pigment and r = no pigment. In carnations, RR offspring make a lot of
red pigment, rr offspring make no pigment and Rr offspring make a small
amount of red pigment, the superior pink. Pink carnations are therefore an
example of
Incomplete dominance
Achondroplasia is a common form of dwarfism caused by an autosomal
dominant mutation In the fibroblast growth factor receptor 3 (FGFR3) gene. Two
copies of the mutant gene or invariably fatal before or shortly after birth. If a
person with achondroplasia marries a person of normal height, what is the
probability that both their first child and second child will have achondroplasia?
1/4
If you are tossing a six-sided die, what is the probability of getting either a 1 or a
2 on your first AND a 1 or a 2 on your second toss?
1/9
In humans, the sickle cell trait is caused by a single defective allele, but sickle
cell disease only occurs in individuals that are homozygous for the sickle cell
allele. A man and a woman each carry the traits, but do not have sickle cell
disease. What is the probability that the first two children will have sickle cell
disease?
1/16
Of the 23 pairs of human chromosomes, 22 pairs are homologous and are found
in both male and females. These are called ____
Autosomes
Trace that are controlled by genes located on the X chromosome are said to be
sex-linked
Occasionally, chromosomes fail to separate during meiosis, leading to daughter
cells that have an abnormal number of chromosomes. This phenomenon is called
nondisjunction
If a human female has two Barr bodies per cell, it is certain that
She developed from a fertilized egg with 3 X chromosomes
Inhumans, if a non-disjunction led to an individual with a genotype of XXY, that
person would
Be male because each cell has one Y chromosome
Which offspring inherit all their mitochondrial DNA from their mother and none
from their father?
Both sons and daughters
